A bogie for supporting a carbody of a railcar and allowing the railcar to run along a rail is provided under a floor of the carbody. The bogie is supported by a primary suspension such that axle boxes each configured to store a bearing for supporting an axle can be displaced in a vertical direction relative to a bogie frame. Generally, the bogie frame includes a cross beam extending in a crosswise direction and a pair of left and right side sills respectively extending from both end portions of the cross beam in a front-rear direction. The primary suspension includes an axle spring constituted by a coil spring provided between the axle box and the side sill located above the axle box (see PTL 1).
According to the bogie as in PTL 1, the bogie frame including the cross beam and the side sills are manufactured by, for example, welding heavyweight steel materials one another. Therefore, problems are that the bogie frame increases in weight, and steel material cost and assembly cost increase. Here, proposed is the bogie in which the side sills are omitted from the bogie frame (see PTL 2). In the bogie of PTL 2, the bogie frame and the axle box are connected to each other by a support mechanism member while maintaining a certain distance between the bogie frame and the axle box. In addition, plate springs extending in the front-rear direction are respectively attached to both end portions of the cross beam of the bogie frame, and both end portions of each of the plate springs are respectively inserted in spring receivers each provided at a lower portion of the axle box.